Fix grizzly compat issue in conducor rpc api

When a new parameter was added in revision
0d5fb06b39e8244429be72f05e2066d24572dc2e, it did not properly account
for rpc client side version control added for compatibility during a
rolling upgrade.  This patch adds the ability to send the older message
version if configured to do so.

Change-Id: Iaadd4890099c12883b4a29a6b049cc672a669f93
Merge "Fix grizzly compat issue in conducor rpc api"